What is the function of kidney dialysis (Renal Replacement Therapy)?

From the Guidelines

Kidney dialysis is a life-saving treatment that artificially performs the kidney's role of filtering waste products, excess fluids, and toxins from the blood when the kidneys can no longer do this effectively, with the most recent guidelines emphasizing the importance of optimal dialysis access to reduce morbidity, mortality, and cost of treatment 1.

Key Aspects of Kidney Dialysis

• The two main types of dialysis are hemodialysis and peritoneal dialysis, each with its own method of filtering waste products from the blood.
• Hemodialysis requires a dialyzer (artificial kidney) to filter out waste and excess fluids, typically needing three sessions per week, each lasting 3-5 hours.
• Peritoneal dialysis uses the lining of the abdomen as a natural filter, with dialysis fluid introduced into the abdominal cavity through a permanently placed catheter.
• Dialysis compensates for lost kidney function by removing waste products, maintaining safe levels of chemicals, and removing excess fluid.

Importance of Dialysis Access

• The creation and maintenance of a dialysis access is vital for reducing morbidity, mortality, and cost of treatment for end-stage renal disease patients 1.
• Arteriovenous fistulas (AVF) are recommended as the preferred vascular access for hemodialysis due to increased patency rates and decreased risk of infection and thrombosis 1.
• The KDOQI guidelines suggest monitoring and surveillance to preempt adverse outcomes and identify lesions with the vascular access before they provoke complications 1.

Medication Management

• Patients on dialysis require medication management, including erythropoietin for anemia, phosphate binders, vitamin D supplements, and blood pressure medications to address complications of kidney failure that dialysis cannot completely resolve 1.
• The quality of dialysis is directly dependent upon the integrity and reliability of the access to the patient’s vascular system, with optimal hemodialysis vascular access providing reliable, complication-free access 1.

From the Research

Kidney Dialysis Function

• The primary function of kidney dialysis is to remove metabolic waste and excess body water, and rebalance electrolytes to sustain life 2.
• There are two main types of dialysis: hemodialysis and peritoneal dialysis, with no significant difference in 5-year mortality rates between the two 2, 3.
• The decision to initiate dialysis is complex and should be based on patient symptoms, laboratory trajectories, patient preferences, and therapy cost and availability, rather than solely on estimated glomerular filtration rate (eGFR) 2, 4.

Dialysis Initiation

• Early dialysis initiation (at an eGFR > 10 mL/min/1.73 m2) is not associated with a morbidity and mortality benefit 3, 4.
• The ideal time to initiate dialysis is when the patient exhibits persistent signs and symptoms of uremia and volume overload, such as nausea, fatigue, dyspnea, and peripheral edema 2.
• In asymptomatic patients with stage 5 chronic kidney disease, dialysis may be safely delayed until the eGFR is at least as low as 5-7 mL/min/1.73 m2, with careful clinical follow-up and adequate patient education 4.

Complications and Challenges

• Cardiovascular and infection-related complications are common in patients undergoing maintenance dialysis 2.
• Hemodialysis catheter-related bloodstream infections and peritonitis are significant concerns, with rates of 1.1 to 5.5 episodes per 1000 catheter-days and 0.26 episodes per patient-year, respectively 2.
• Chronic kidney failure-related systemic complications, such as anemia, hyperphosphatemia, hypocalcemia, and hypertension, often require pharmacologic treatment 2.